Luigi Nono's work isn't often performed in this country. And yet before his death in 1990, the Italian composer was one of the leading figures of the avant-garde. As part of its adventurous series of concert performances, Almeida Opera offered a programme of his music, exploring its variety through pieces dating from the early 1960s and late 1980s.

The uniqueness of Nono's output is its relationship with political ideology. A committed Marxist, he used his modernist musical language to express the inequalities experienced by the working classes of postwar Europe. His search for political engagement led him away from the conventions of the concert hall.

La Fabbrica Illuminata (The Enlightened Factory), written in 1964 for solo soprano and tape, was Nono's first major experiment in mixing live and electronic sounds. At the Almeida, Sarah Leonard and sound projectionist Alvise Vidolin created a visceral performance. Leonard was at the centre of a sonic maelstrom. The tape track was made from songs and speeches recorded in an Italian factory, conveying a sense of protest with cinematic vividness.

Leonard's virtuosic vocal line joined this dissenting chorus, as if her work was a metaphor for the labour of the factory-workers. But the end of the piece was more ambivalent: a solo, hymn-like melody for the live soprano that was both a cry of sympathy and a message of hope.

Compared with the conflict and violence of this music, Nono's late instrumental pieces seem to inhabit a different world. But performances of Post-Prae-Ludium per Donau (composed in 1987 for solo tuba and live electronics) and Hay que Caminar Sonando (his last completed piece, scored for two violins) demonstrated connections between the different periods. The later pieces replace political struggle with a search for sound itself. Every sound produced by Melvyn Poore's tuba was transformed by live electronics. From bird-like calls in the instrument's highest register to the quiet thunder of its lowest notes, the texture of the music was never stable.

The delicate soundworld of Hay que Caminar Sonando achieves a similar effect with purely acoustic means: each violinist is a distorting mirror of the other, as tiny changes of dynamic and pitch are reflected between the two parts. It is as if the music is somehow listening to itself. The focus of David le Page's and Patrick Savage's interpretation made the piece an enigmatic and moving experience.